1. Field of the Invention
The present invention relates to a laser scanning device deflecting an incident light in a predetermined direction.
2. Description of the Related Art
Generally, image forming apparatuses, such as a laser printer, a photocopier, a scanner, and a multifunction apparatus, have a laser scanning device.
In the laser scanning device, a light projected from a light source is deflected in a predetermined direction by a specular surface of a rotating polygonal mirror that is rotated at a high speed. The deflected light passes through a predetermined optical system and enters a photoconductive medium, such as a photoconductive drum.
As the image forming apparatus tends toward high-speed performance, rotational speed of the rotating polygonal mirror increases. When the rotating polygonal mirror is rotated at a high speed, ambient air of the rotating polygonal mirror, which contains inner dust, generates a fast air current in a main body of the laser scanning device. Therefore, the dust scattered by the air current may attach to the specular surface. When the specular surface is thus contaminated, optical reflexibility decreases, accordingly deteriorating optical deflection.
Some of the laser scanning devices further include a light-blocking unit to prevent the light from being unintentionally projected to the outside during maintenance of the apparatus or by malfunctioning of the apparatus. However, the conventional light-blocking unit having a plurality of parts, such as a resilient member, a shutter, and a driving motor, requires a complicated structure and a dedicated driving source.
Accordingly, a need exists for a laser scanning device that substantially prevents contamination of a rotating polygonal mirror.